Current applications for many chemicals and biological substances require the use of a pipette to transfer measured quantities of these substances from the containers in which they were purchased to the containers in which they will ultimately be used. In the case of some biological substances, this presents a substantial contamination risk. The contamination risk applies both to the substances remaining in the purchased container and to those transferred to the ultimate use container. This contamination risk involves not only the potential loss of the experiment or long-term procedure being carried out, but substantial dollar risk as well, since the chemicals or biological substances that may be contaminated can be very costly (viz. over $100.00 per 500 ml bottle).
The risk of contamination is incurred by opening the bottle, inserting a pipette into the bottle, and subsequently inserting the same pipette into the ultimate use container. All of these operations, even when carried out under a sterile hood, can allow particulate, bacterial, or viral contamination to the initial bottle and/or the ultimate use container. A fixed wall pipette must draw air into its upper end as it empties. This influx of air can add to the contamination hazard as it impinges upon the chemicals or biological materials being dispensed. These problems are compounded when research personnel fail to observe proper sterile procedures such as wearing sterile gloves, performing such transfers under a sterile hood, utilizing sterile pipettes, and changing pipettes between transfers.
The basic technique of pipetting to transfer precise quantities of a liquid is cumbersome, inherently non-sterile and time-consuming. To help alleviate these problems, prior art in this area encompasses an array of mechanical devices and methodologies, none of which address the underlying problem of eliminating the need to pipette at all. For example U.S. Pat. No. 4,748,859 discloses a disposable pipette tip; U.S. Pat. No. 5,223,218 concerns control of an automated pipetter; and U.S. Pat. No. 5,210,927 relates to a pipette filter inserter.
The use of disposable glass pipettes for such transfers constitutes a "sharps" disposal problem since they cannot be cleaned and reused cost-effectively. This "sharps" hazard is of particular concern when the pipettes in question have been used to transfer toxic chemicals or biohazardous materials. Such "sharps" must be disposed of in an approved manner, which can be very expensive and cumbersome.
Many chemicals or biological materials are stored in a frozen state or kept refrigerated and must be warmed to room temperature prior to use. It has been shown that, when freezing and thawing biological materials such as blood plasma, improvements of up to 30% in recoverable protein levels can be achieved by rapid freezing and thawing, as compared to conventional freezing and thawing methodologies. Since, in many instances, less than the entire contents of the container may be used for each application, the contents are subject to repeated thawing/freezing or warming/cooling cycles. These repeated, comparatively slow, thermal cycles can degrade the chemicals or biological substances and are very time-consuming when the materials are stored in 500 ml or 1 liter bottles.
Many chemicals or biological substances have high vapor pressures and tend to lose their constituent gases unless stored in gas-tight environments. The loss of these constituent gases affects the pH of the chemicals or biological substances and renders them useless.
Finally, some chemicals or biological substances are light sensitive and must be kept shielded from light. Exposure to light can cause the chemicals or biological substances to decompose and render them useless.